<div class="refentry" lang="en" xml:lang="en"><a id="glClipPlane"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glClipPlane — specify a plane against which all geometry is clipped</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table><tr><td><code class="funcdef">void <b class="fsfunc">glClipPlane</b>(</code></td><td>GLenum  </td><td><var class="pdparam">plane</var>, </td></tr><tr><td> </td><td>const GLdouble *  </td><td><var class="pdparam">equation</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>plane</code></em></span></dt><dd><p>
                    Specifies which clipping plane is being positioned.
                    Symbolic names of the form <code class="constant">GL_CLIP_PLANE</code><span class="emphasis"><em>i</em></span>,
                    where <span class="emphasis"><em>i</em></span> is an integer between 0 and <code class="constant">GL_MAX_CLIP_PLANES</code>
                    <math overflow="scroll">

                        <mn>-1</mn>
                    </math>,
                    are accepted.
                </p></dd><dt><span class="term"><em class="parameter"><code>equation</code></em></span></dt><dd><p>
                    Specifies the address of an array of four double-precision floating-point values.
                    These values are interpreted as a plane equation.
                </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
            Geometry is always clipped against the boundaries of a six-plane frustum
            in <span class="emphasis"><em>x</em></span>, <span class="emphasis"><em>y</em></span>, and <span class="emphasis"><em>z</em></span>.
            <code class="function">glClipPlane</code> allows the specification of additional planes,
            not necessarily perpendicular to the <span class="emphasis"><em>x</em></span>, <span class="emphasis"><em>y</em></span>, or <span class="emphasis"><em>z</em></span> axis,
            against which all geometry is clipped.
            To determine the maximum number of additional clipping planes, call
            <a class="citerefentry" href="glGetIntegerv"><span class="citerefentry"><span class="refentrytitle">glGetIntegerv</span></span></a> with argument <code class="constant">GL_MAX_CLIP_PLANES</code>. All
            implementations support at least six such clipping planes.
            Because the resulting clipping region is the intersection
            of the defined half-spaces,
            it is always convex.
        </p><p>
            <code class="function">glClipPlane</code> specifies a half-space using a four-component plane equation.
            When <code class="function">glClipPlane</code> is called,
            <em class="parameter"><code>equation</code></em> is transformed by the inverse of the modelview matrix
            and stored in the resulting eye coordinates.
            Subsequent changes to the modelview matrix have no effect on the
            stored plane-equation components.
            If the dot product of the eye coordinates of a vertex with the
            stored plane equation components is positive or zero,
            the vertex is <span class="emphasis"><em>in</em></span> with respect to that clipping plane.
            Otherwise, it is <span class="emphasis"><em>out</em></span>.
        </p><p>
            To enable and disable clipping planes, call
            <a class="citerefentry" href="glEnable"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a> and <a class="citerefentry" href="glDisable"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a> with the argument
            <code class="constant">GL_CLIP_PLANE</code><span class="emphasis"><em>i</em></span>,
            where <span class="emphasis"><em>i</em></span> is the plane number.
        </p><p>
            All clipping planes are initially defined as (0, 0, 0, 0) in eye coordinates
            and are
            disabled.
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
            It is always the case that <code class="constant">GL_CLIP_PLANE</code>
            <math overflow="scroll"><mi mathvariant="italic">i</mi></math>
            = <code class="constant">GL_CLIP_PLANE0</code> +
            <math overflow="scroll"><mi mathvariant="italic">i</mi></math>.
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
            <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>plane</code></em> is not an accepted value.
        </p><p>
            <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glClipPlane</code>
            is executed between the execution of <a class="citerefentry" href="glBegin"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>
            and the corresponding execution of <a class="citerefentry" href="glEnd"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
            <a class="citerefentry" href="glGetClipPlane"><span class="citerefentry"><span class="refentrytitle">glGetClipPlane</span></span></a>
        </p><p>
            <a class="citerefentry" href="glIsEnabled"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_CLIP_PLANE</code><span class="emphasis"><em>i</em></span>
        </p></div>
        {$pipelinestall}{$examples}
        <div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
            <a class="citerefentry" href="glEnable"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>
        </p></div><div class="refsect1" lang="en" xml:lang="en"><div id="Copyright"><h2>Copyright</h2><p>
            Copyright © 1991-2006
            Silicon Graphics, Inc. This document is licensed under the SGI
            Free Software B License. For details, see
            <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
        </p></div></div></div>
